“HFC refrigerant” such as R410A, which is non-flammable, has conventionally been used as refrigerant of a refrigeration cycle for an air-conditioning apparatus. This R410A has zero ozone depleting potential (hereinafter, referred to as “ODP”) unlike the conventional “HCFC refrigerant” such as R22, and does not deplete the ozone layer. However, R410A has a high a global warming potential (hereinafter, referred to as “GWP”).
Consequently, as one of measures to prevent global warming, replacing HFC refrigerant, having a high GWP, such as R410A with refrigerant having a low GWP has been considered.
As refrigerant having a low GWP to be used, HC refrigerant such as R290 (C3H8, propane) and R1270 (C3H6, propylene), which are natural refrigerant, has been suggested. However, unlike R410A, which is non-flammable, HC refrigerant is highly flammable, and thus care should be taken for leakage of the refrigerant.
Further, as refrigerant having a low GWP, for example, R32 (CH2F2, difluoromethane), which is HFC refrigerant that does not have carbon double bond in its composition and has lower GWP than that of R410A, has been suggested.
Suggestion has also been made for halogenated hydrocarbon, which is a different type of HFC refrigerant than R32 and has carbon double bond in its composition. Such halogenated hydrocarbon may be, for example, HFO-1234yf (CF3CF═CH2, tetrafluoropropene) and HFO-1234ze (CF3—CH═CHF). The HFC refrigerant that has carbon double bond is often referred to as “HFO” by using “O” for olefin (unsaturated hydrocarbon having carbon double bond is called olefin) to be distinguished from HFC refrigerant such as R32 that does not have carbon double bond in the composition.
Although being not as highly flammable as HC refrigerant such as R290 (C3H8, propane), which is natural refrigerant, those types of HFC refrigerant (including HFO refrigerant) having a low GWP are mildly flammable unlike R410A, which is non-flammable. Thus, care should also be taken for leakage of the refrigerant as similar to R290. Hereinafter, refrigerant having flammability, even when its level is mild, is referred to as “flammable refrigerant”.
To prevent refrigerant concentration in a room from exceeding a specific value in the event of leakage of flammable refrigerant, a refrigerant filling level is stipulated in the international standard (IEC 60335-2-40).
That is, in the international standard, an acceptable level of refrigerant (Mmax) per room is stipulated by an equation “Mmax=2.5×(LFL)1.25×H0×A0.5”, which is a function of a lower flammability limit (LFL) of refrigerant, a floor area (A), and an installation height of device (H0). The installation height (H0) is defined as “0.6 m” for a floor installation type, “1.8 m” for a wall mounted type, “1.0 m” for a window mounted type, and “2.2 m” for a ceiling mounted type.
To satisfy the above equation, a split type air-conditioning apparatus is disclosed that compares a value of installation floor area stored in the apparatus and an input value of installation floor area for actual installation (after subtracting an installation area of furniture), and gives an instruction to promote ventilation of the room or to collect a portion of refrigerant into a refrigerant storing tank when the input value is smaller than the stored value (when the equation is not satisfied) (for example, see Patent Literature 1).